Positive sound track in multilayer film



'NOV. 11, 1947. c, @ELL I 2,430,565

POSITIVE SOUND TRACK IN MULTILAYER FILM Filed Dec. 29, 1945 SOUND EXPOJURE FROM NEGA T/ VE i BLUE GREEN RED BLUE SENSITIVE GREEN SENSITIVE RED SENSITIVE r- SUPPORT l3 l4 YELLOW FILTER SOUND TRACK FIXED AND PICTURE AREA COLOR DEVELOPfD FERR/CmN/DE AND HAL/DE, AND

SHORT HYPO TREATMENT REDEVELOPMENT or sou/vb mac/r AND HYPO TREATMENT CHARLES H. GUELL I INVENTOR TTORNE S I Patented Nov. 11, 1947 UNTE ES POSITIVE SOUND TRACK IN MULTILAYER FILM Application December 29, 1945, Serial No. 637,895

2 Claims.

This invention relates to photographic color films having sound tracks thereon and particularly to a method for producing sound records on such films.

record. The picture areas of the film are exposed in the usual way to a positive scene or image. The sound track and picture areas are developed in the usual way in a normal black and white It is Well known that a positive sound track 5 developer to produce negative silver images in the printed from a negative is capable of producing picture areas and a positive sound track record noticeably better sound reproduction than a track in the sound track area. Residual undeveloped which is made by reversal in a photographic film. silver halide is present in both the picture and In multi-layer color films, it has hitherto been sound track areas of the film at this stage. necessary, in general, to form the sound track by The sound track area of the film is then fixed reversal. This places a severe limitation on the by edge application of a special hypo bath to quality of the sound produced. the sound track area only. This may be accom- 'It is therefore the principal object of the presplished by dipping the edge of the film into the ent invention to provide a method for producing hypo solution or by application of the fixing bath a positive sound track in a multi-layer photoby means of an applicator which restricts the sographic film which is processed by reversal. A lution to the sound track area. The film is then second object is to provide a method for producwashed and the residual silver halide in the ing a silver sound record directly in multi-layer sound track area only is thereby removed leavfilm rather than by reversal. A still further obingresidual unexposed silver halide in the picture ject is to provide a method for producing clean .20 area of the film. highlight in the sound record. Other objects The film then continues through its regular will appear from the following description of our processing for the production of reversed images invention. in the picture area of the film by selective reex- These objects are accomplished by the use of posure and color development of the picture areas. my method which in its broader aspects involves The film is then treated with a bleach solution the printing of a negative sound record onto a of an alkali metal ferrioyanide, an alkali metal multi-layer film followed by black and white dehalide, in the usual way, to convert the silver velopment of both the sound track and picture images in both the picture and sound track areas areas of the film and edge fixing of the sound to silver halide. track areas so that the picture areas may be At this stage in the process, another of the processed by reversal in the usual way. novel features of my invention is performed.

The accompanying drawing is a flow chart The film is treated in a Wea yp for a short showing in sectional form the film at various period of time of the order of 30 seconds to two stages in my process. minutes to remove the silver halide formed from A multi-layer film which is processed by rethe colloidal silver of the filter layer and from versal is described in Mannes, Godowsky and the silver that was produced as fo in the nega- Wilder U. S. Patent 2,252,718, granted August 19, tive or first developer. This treatment removes 1941, and my process may be applied to a film of only the silver halide produced from the fine this type. The multi-layer film described in the ai S lve present in the film and does not Mannes, Godowsky and Wilder patent has three remove the silver halide of the sound track or superposed light-sensitive layers sensitive, respecof the picture records. This treatment results tively, to the red, green and blue spectral regions, in clean highlights for the sound track record. the blue-sensitive layer being outermost or far- The contrast of the sound image may b thest from the support. After exposure and n strolled y e t e th of the weak hypo soluative development of this film, the emulsion tion used at this point. Treatment in a 2% hypo layers are separately exposed and color developed solution for two minutes, followed by redevelopto produce reversed dye images of the proper ment, can give a sound track with a maximum color in the separate layers. The metallic silver density of above t s is Satisfactory for Variand the coloring material, such as colloidal silver l e t acks- By using a strong r yp 1 of the yellow filter layer, are then removed by 0 tion (3%-8%), the maximum density can be converting the silver to silver ferricyanicle and reduced to 1.5, which is satisfactory for variable treatment of the film with hypo. density sound tracks.

According to the present invention, the sound After the weak hypo treatment, the sound track track is printed in one or more layers of the sound record is developed byedge application rorab0u-t track area of the film from a negative sound 5 15 to 30 seconds with a strong black and white developer. This produces a redeveloped positive sound record of metallic silver in the sound track area of the film without affecting the silver halide in the picture area. Treatment of the film is then completed by additional fixing for about two minutes. This removes the silver halide from the picture area of the film. The normal washin and drying operations then follow.

My invention will now be described by reference to the accompanying drawing.

As shown in the first stage of the drawing, a multilayer film having a support ID of any suitable material, such as cellulose nitrate or cellulose acetate, has coated thereon gelatino silver halide emulsion layers ll, 12 and I3, sensitive,

respectively, to the red, green and blue spectral regions. The usual yellow filter layer l4, preferably of colloidal silver, is coated between emulsion layers l2 and 13 to prevent action of blue light on the underlying emulsion layers I I and I2.

The film is exposed to a natural scene or image, the exposing light being represented by the arrows labeled blue, green and red. The sound track area is exposed from a negative sound track record and all of the images are developed in a black and white developer to produce the negative silver picture records 15 and positive silver sound record Hi. The sound track record 16 is indicated as being in all of the emulsion layers H, [2 and I3 although the sound record may be restricted to less than all of the emulsion layers by use of exposing light of a suitable color.

The sound track area of the film is then fixed by edge application of a hypo solution to the sound track area, thus removing the residual silver halide from the sound track area while leaving the silver sound record iii in the film. The film is carried through the usual color development steps to produce a cyan and metallic silver image I7 in the bottom emulsion layer, a magenta and metallic silver IS in the middle emulsion layer and a yellow and metallic silver image in the top emulsion layer as shown in the second stage of the drawing. l

The film is then treated with a ferricyanide and halide bleaching bath such as an alkaline solution of potassium ferricyanide and potassium bromide to convert the metallic silver images to silver bromide. This is followed by a short weak hypo treatment which removes the line grain silver from the film. After this treatment, as shown in the third stage of the drawing, the film contains positive silver bromide sound image 2e, negative silver bromide picture records 2| and cyan and silver bromide image 22, magenta and silver bromide image and yellow and silver bromide, image 2:1 in the corresponding layers of the film. The colloidal silver of the filter layer 14 has been removed leaving a clear gelatin layer, as shown at 25 in the third stage of the drawing. Any fog silver produced in the first developer has also been removed.

The sound track area of the film is then redeveloped by edge application to produce redeveloped silver sound images 26 in the sound area of the film, as shown in the fourth stage of the drawing. The film is then subjected to a longer hypo treatment to remove the silver halide image 2| in the picture areas of the film and the silver halide associated with the dye images 22,23 and 24. This leaves pure cyan dye image 2! in the bottom layer of the film, magenta dye image 28 in the middle layer of the film and yellow dye '4 image 29 in the top layer of the film, as shown in the fourth stage of the drawing.

The following baths may be used in processing the film according to my invention.

The first or negative developer may have the following composition, the film being developed for approximately 10 minutes at 20 C. in this solution.

Grams Monomethylp-amino phenol sulphate 6 Hydroquinone 10 Sodium sulfite 50 Sodium carbonate 30 Potassium bromide 5 Potassium thiocyanate 0.5 Water to 1 liter.

After development of the film in this solution, the sound track area is fixed by edge application in a hypo bath of the following composition:

Grams Ammonium thiosulfate 200 Sodium sulfite 20 Water to 1 liter.

The picture area of the film is then color developed by selective exposure and development, as described, for example, on page 2 of U. S.

'Patent 2,252,718. The film is then treated in a ferricyanide bleach bath, for example, a bleach bath of the following composition:

minutes in a weak hypo solution of the following composition:

Grams Sodium thiosulfate 20 Sodium sulfite 1 Water to 1 liter.

The sound track record is then redeveloped by edge application for 15 to 30 seconds with a strong black and white developer of the following composition:

The treatment of the film in a hypo bath of the usual composition, such as that stated above, is then continued for about two minutes, and the film is washed and dried in the usual way.

Numerous modifications may be made within the scope of my invention which is to be understood as comprising all features falling within the scope of the appended claims.

Iclaim:

1. The method of producing a positive sound track in a multi-layer photographic film having superposed emulsion layers sensitive, respectively, to different regions of the visible spectrum of which an area is suitable for sound track recording and another area is suitable for picture recording, which comprises forming latent images in the respective areas by exposure of the sound track area to a negative sound image and exposure of the picture area to a positive picture image, developing said latent images in a blackand-white developer to form a positive silver sound track in the sound track area and negative silver picture images in the picture area, removing unexposed silver halide from the sound track area only, selectively exposing the layers to light of a color to which each is sensitive and color developing them to produce positive picture images in the picture areas, treating the film with a solution of potassium ferricyanide and potassium bromide to convert the silver in all layers and areas to silver bromide, subjecting the film to treatment with a weak hypo solution for 30 seconds to two minutes, redeveloping the sound track area only to metallic silver in a black-andwhite developer and removing the remaining silver halide from the film.

2. In the production of a positive sound track in a multi-layer photographic film having superposed emulsion layers sensitive, respectively, to difierent regions of the visible spectrum of which an area is suitable for sound track recordin and another area is suitable for picture recording, by forming latent images in the respective areas by exposure of the sound track area to a negative sound image and exposure of the picture area to a positive picture image, developing said latent images in a black-and-white developer to form a positive silver sound track in the sound track area and negative silver picture images in the picture area, removing unexposed silver halide from the sound track area only, selectively exposing the layers to light of a color to which each is sensitive and color developing them to produce positive picture images in the picture areas, treating the film with a solution of an alkali metal ferricyanide and an alkali metal halide to convert the silver in all layers and areas to silver halide, subjecting the film to treatment with a weak hypo solution for approximately 30 seconds to two minutes, redeveloping the sound track area only to metallic silver in a black-andwhite developer and removing the remaining silver halide from the film, the method of controlling the contrast of the sound track which comprises varying the concentration of hypo in said weak hypo solution from about 2% to about 8%.

CHARLES H. GUELL.

REFERENCES CITED The following references'are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,178,882 Schneider Nov. 7, 1939 2,220,178 Schneider Nov, 5, 1940 FOREIGN PATENTS Number Country Date 362,394 Great Britain 1931 362,876 Great Britain 1932 

